The present invention relates generally to the field of polymer chemistry. More particularly, it concerns specific formulations of monovinylarene-conjugated diene block copolymers adapted for blendability with other polymers while still maintaining desired performance characteristics. In some embodiments, such compositions are provided that are particularly resistant to blocking when stored in pellet form.
Various formulations of monovinylarene-conjugated diene block copolymers have long been researched and sought after, including blends with other polymers such as, but not limited to, crystal polystyrene and acrylate polymers. It is generally desirable that such monovinylarene-conjugated diene polymers have low cost, high clarity, low haze, tough physical characteristics, and be easy to handle, store and process.
Unfortunately, measures taken to address a given objective are often at the expense of other objectives. For example, adding increased amounts of polystyrene or acrylate polymers to a clear monovinylarene-conjugated diene block copolymer system may result undesirably in degraded optical characteristics such as haze. Also, until a particular polymer formulation is actually synthesized and tested, it is often difficult or impossible to predict what the physical properties will be.
Since polymers are often shipped and stored in pellet form, the blocking characteristics of a polymer system can also be a critical factor, even where an otherwise suitable polymer system has been identified. In this context, blocking refers to any tendency of a material to agglomerate, especially in the case of resin pellets sticking to themselves during storage or processing.
There continues to be a need for compositions and methods directed at achieving objectives including the foregoing, particularly in a cost efficient manner.